Prof. Dietmar Dommenget

ENSO: non-linear dynamics

Supervisor(s): Dietmar Dommenget
Field of study: Climate Dynamics / Atmospheric Science / Oceanography

The El Nino Southern Oscillation (ENSO) mode is often described by a simple linear recharge oscillator model. In this model we have an out-of-phase relation between the sea surface temperature (SST) and the thermocline depth (h). The observed phase space of SST and h has some interesting non-linear characteristics. That is, El Ninos are stronger and shorter than La Ninas. This project will aim at analysing this dynamical ENSO phase space with a focus on it’s non-linear behaviour and test different hypothesis on what is causing non-linear ENSO behaviour and predictability.

ENSO and tropical basin interactions in idealised worlds

Supervisor(s): Dietmar Dommenget
Field of study: Climate Dynamics / Atmospheric Science / Oceanography

The El Nino Southern Oscillation (ENSO) mode is the leading mode of interannual variability. It interacts with the other ocean basins, which influences its strength, periodicity, predictability and non-linear behaviour. The project will use a fully coupled ocean-atmosphere GCM to simulate ENSO in idealised world with different ocean basins and land distributions. The different simulations will help to understand what is controlling the important aspects of ENSO dynamics.

ENSO: CMIP-model ocean-dynamics biases

Supervisor(s): Dietmar Dommenget
Field of study: Climate Dynamics / Stochastic Variability

The El Nino Southern Oscillation (ENSO) mode is the most important mode of natural variability on time scales from seasons to a few years. State-of-the-art climate models (e.g. CMIP6 models) can simulate this mode, but the dynamics and feedback that control this mode are significantly biased in CMIP6 model simulations. Previous studies have mostly focussed on biases in the atmospheric dynamics. This project will aim at oceanic biases in CMIP5 model simulations. The project will analyse the CMIP6 database and focus on how well the models simulate aspect of the ENSO ocean mean state and dynamics.

Tropical Circulation Changes and Variability in the Framework of the Moist Static Energy Balance

Supervisor(s): Dietmar Dommenget
Field of study: Climate Dynamics

The Framework of the Moist Static Energy Balance (MSEB) is simple approach to diagnose the large-scale tropical circulation (vertical motion) based on the current temperature, moisture and horizontal wind distribution. This is helpful in understanding what is driving tropical circulation changes on monthly or longer time scales. Fan and Dommenget 2020 have presented a simple MSEB model for applications to large-scale climate variability. The project aims at applying this approach to a number of different aspects of climate change and variability. It could, for instance, be applied to monsoon changes, ENSO, tropical basin interactions or to idealized SST changes and the atmospheric response to it. The project will be a combination of data analysis, model simulations and analysis.

The physical phase space of climate modes

Supervisor(s): Dietmar Dommenget
Field of study: Climate Dynamics / Stochastic Variability

Natural climate variability is often characterised by climate modes, such as the El Nino Southern Oscillation (ENSO) or the Madden Julian Oscillation (MJO). The idea of a climate mode is that of a re-occurring oscillation that has some predicable nature, like a damped physical oscillator, such as a pendulum or a swing. Such physical oscillators are often described by a 2-dimensional dynamical phase space, to highlight the nature of the repeating cycle. This has been done for ENSO, and it has been shown to be quite interesting. The aim of this study is to apply this concept to other climate modes such as the MJO, or the Quasi-Biannual Oscillation (QBO).

A Conceptual model of global precipitation changes

Supervisor(s): Dietmar Dommenget
Field of study: Climate Dynamics / Atmospheric Science
The future climate change projections, such as published in the IPCC report, are based on state of the art coupled general circulation (CMIP) models. These models predict a complex pattern of precipitation changes in response to global warming. Conceptually understanding how this pattern comes about is challenging, but not impossible. The Globally Resolved Energy Balance (GREB) model (aka Monash Simple Climate Model), that can simulate the global climate response to external forcing can simulate the CMIP models precipitation pattern if forced with atmospheric circulation and evaporation changes from CMIP models. The aim of this project is
develop a good conceptual model to explain this precipitation pattern.

Webpages:
* GREB model
* Monash Simple Climate Model

Simple Climate Model Projects

Supervisor(s): Dietmar Dommenget
Field of study: Climate Dynamics / Stochastic Variability

We have developed the simple climate model: Globally Resolved Energy Balance (GREB) model (aka Monash Simple Climate Model), that can simulate the global climate response to external forcing. It can compute 100,000yrs of simulation per day on a standard PC computer. Thus, it is a nice and simple tool that allows for wide range of studies. Projects examples could be on: simulating the past climates of the last 500 Mill. yrs., do geo-engineering studies, build strange worlds or exo-planets or developing new elements like better precipitations at higher latitudes, soil moisture, aerosols or atmospheric circulation response. Detailed projects with the GREB model will be formulated together with the student, as there are simply to many different things that could be done with this model to list them all here.

Webpages:

Simulation of Ice-Age cycles with the GREB Model

Supervisor(s): Dietmar Dommenget
Field of study: Climate Dynamics / Atmospheric Science

We have developed the simple climate model: Globally Resolved Energy Balance (GREB) model (aka Monash Simple Climate Model), that can simulate the global climate response to external forcing. It can compute 100,000yrs of simulation per day on a standard PC computer. An important aspect of the last few million years of climate variability are the global 100kyrs ice-age cycles. The aim this project is to simulate the past million years of climate variability with the GREB model and try to gain understanding on what controls the global 100kyrs ice-age cycles. This project will be a combination of literature study, climate model development and analysis of model simulations.

Webpages:

For further information, contact Dietmar Dommenget